Finger.EXE Execution — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), omkar72, oscd.community. Source status: test; severity: high. Source dates: 2021-02-24 / 2024-06-27.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0c50cac3cc6a96ad9b064d2d5e98e15f769174d457d88ba0f7b1841e27364745

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Finger.EXE Execution
id: af491bca-e752-4b44-9c86-df5680533dbc
related:
    - id: c082c2b0-525b-4dbc-9a26-a57dc4692074
      type: similar
    - id: 2fdaf50b-9fd5-449f-ba69-f17248119af6
      type: similar
status: test
description: |
    Detects execution of the "finger.exe" utility.
    Finger.EXE or "TCPIP Finger Command" is an old utility that is still present on modern Windows installation. It Displays information about users on a specified remote computer (typically a UNIX computer) that is running the finger service or daemon.
    Due to the old nature of this utility and the rareness of machines having the finger service. Any execution of "finger.exe" can be considered "suspicious" and worth investigating.
references:
    - https://twitter.com/bigmacjpg/status/1349727699863011328?s=12
    - https://app.any.run/tasks/40115012-a919-4208-bfed-41e82cb3dadf/
    - http://hyp3rlinx.altervista.org/advisories/Windows_TCPIP_Finger_Command_C2_Channel_and_Bypassing_Security_Software.txt
author: Florian Roth (Nextron Systems), omkar72, oscd.community
date: 2021-02-24
modified: 2024-06-27
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - OriginalFileName: 'finger.exe'
        - Image|endswith: '\finger.exe'
    condition: selection
falsepositives:
    - Admin activity (unclear what they do nowadays with finger.exe)
level: high
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_finger_execution/info.yml

Original YAML and metadata in JSON

False positives

• Admin activity (unclear what they do nowadays with finger.exe)

Source references

• https://twitter.com/bigmacjpg/status/1349727699863011328?s=12
• https://app.any.run/tasks/40115012-a919-4208-bfed-41e82cb3dadf/
• http://hyp3rlinx.altervista.org/advisories/Windows_TCPIP_Finger_Command_C2_Channel_and_Bypassing_Security_Software.txt